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Nazmutdinov RR, Bronshtein MD, Zinkicheva TT, Chi Q, Zhang J, Ulstrup J. Modeling and computations of the intramolecular electron transfer process in the two-heme protein cytochrome c(4). Phys Chem Chem Phys 2012; 14:5953-65. [PMID: 22430606 DOI: 10.1039/c2cp24084j] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The di-heme protein Pseudomonas stutzeri cytochrome c(4) (cyt c(4)) has emerged as a useful model for studying long-range protein electron transfer (ET). Recent experimental observations have shown a dramatically different pattern of intramolecular ET between the two heme groups in different local environments. Intramolecular ET in homogeneous solution is too slow (>10 s) to be detected but fast (ms-μs) intramolecular ET in an electrochemical environment has recently been achieved by controlling the molecular orientation of the protein assembled on a gold electrode surface. In this work we have performed computational modeling of the intramolecular ET process by a combination of density functional theory (DFT) and quantum mechanical charge transfer theory to disclose reasons for this difference. We first address the electronic structures of the model heme core with histidine and methionine axial ligands in both low- and high-spin states by structure-optimized DFT. The computations enable estimating the intramolecular reorganization energy of the ET process for different combinations of low- and high-spin heme couples. Environmental reorganization free energies, work terms ("gating") and driving force were determined using dielectric continuum models. We then calculated the electronic transmission coefficient of the intramolecular ET rate using perturbation theory combined with the electronic wave functions determined by the DFT calculations for different heme group orientations and Fe-Fe separations. The reactivity of low- and high-spin heme groups was notably different. The ET rate is exceedingly low for the crystallographic equilibrium orientation but increases by several orders of magnitude for thermally accessible non-equilibrium configurations. Deprotonation of the propionate carboxyl group was also found to enhance the ET rate significantly. The results are discussed in relation to the observed surface immobilization effect and support the notion of conformationally gated ET.
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Affiliation(s)
- Renat R Nazmutdinov
- Kazan National Research Technological University, 420015 Kazan, Republic Tatarstan, Russian Federation
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Zhang J, Kuznetsov AM, Medvedev IG, Chi Q, Albrecht T, Jensen PS, Ulstrup J. Single-Molecule Electron Transfer in Electrochemical Environments. Chem Rev 2008; 108:2737-91. [PMID: 18620372 DOI: 10.1021/cr068073+] [Citation(s) in RCA: 252] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Pereira AS, Tavares P, Folgosa F, Almeida RM, Moura I, Moura JJG. Superoxide Reductases. Eur J Inorg Chem 2007. [DOI: 10.1002/ejic.200700008] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Alice S. Pereira
- Requimte, Centro de Química Fina e Biotecnologia, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Quinta da Torre, 2829‐516 Caparica, Portugal, Fax: +351‐21‐2948550
| | - Pedro Tavares
- Requimte, Centro de Química Fina e Biotecnologia, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Quinta da Torre, 2829‐516 Caparica, Portugal, Fax: +351‐21‐2948550
| | - Filipe Folgosa
- Requimte, Centro de Química Fina e Biotecnologia, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Quinta da Torre, 2829‐516 Caparica, Portugal, Fax: +351‐21‐2948550
| | - Rui M. Almeida
- Requimte, Centro de Química Fina e Biotecnologia, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Quinta da Torre, 2829‐516 Caparica, Portugal, Fax: +351‐21‐2948550
| | - Isabel Moura
- Requimte, Centro de Química Fina e Biotecnologia, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Quinta da Torre, 2829‐516 Caparica, Portugal, Fax: +351‐21‐2948550
| | - José J. G. Moura
- Requimte, Centro de Química Fina e Biotecnologia, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Quinta da Torre, 2829‐516 Caparica, Portugal, Fax: +351‐21‐2948550
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